To meet the demand for wireless data traffic having increased since deployment of 4th generation (4G) communication systems, efforts have been made to develop an improved 5th generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
The present disclosure relates to a method and an apparatus for searching for a cell of a terminal in a communication system supporting beamforming.
In a cellular communication system supporting beamforming, a terminal and a base station may form a plurality of beams to transmit and receive signals. The terminal and the base station do not form all beams at the same time and form only a single beam or only some beams at a time when communicating using beamforming. In particular, each of the terminal and the base station may select a best beam from among the plurality of beams according to a beamforming protocol, and transmit and receive signals using the selected beam.
It is common that the best beam of the terminal and the base station is changed according to the movement of the terminal, and, when the terminal moves by longer than a threshold distance, the best base station for the terminal may be changed. Accordingly, when the terminal moves, the terminal should search for a best base station and select a best beam for the searched best base station in order to maintain high communication efficiency between the terminal and the base station. The terminal may measure signals received in different directions while changing the directions of reception beams, in order to search for the best base station and the best beam for the base station. However, when the directions of the reception beams are changed to measure the received signals, the terminal cannot communicate with the best base station that the terminal is currently communicating with.
Accordingly, the related-art terminal requests a serving base station to allocate a gap time in order to search for a neighbor base station, and searches for a neighbor base station and measures the intensity of beams of the searched neighbor base station during the gap time allocated by the serving base station. However, the above-described method wastes time during the process in which the terminal requests the serving base station to allocate the gap time and receives a response to the request, and does not allow the terminal to communicate with the serving base station during the gap time. Therefore, there is a problem that reliable communication cannot be guaranteed.